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Molecular Geometry and Bonding Theories Katherine Shin & Peedith Maldonado. Chapter 9. Dedication Page. Our lovely Chemistry teacher, Ms. Ramona Ricks = P.S- Give us an A Please. 9.1 Molecular Shapes.
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Molecular Geometry and Bonding Theories Katherine Shin & Peedith Maldonado Chapter 9
Dedication Page Our lovely Chemistry teacher, Ms. Ramona Ricks = P.S- Give us an A Please.
9.1 Molecular Shapes • The overall shape of a molecule is determined by its bond angles, the angles made by the lines joining the nuclei of the atoms in the molecule. • The possible shapes of Abn molecules depend on the value of “n.” • Examples: AB2 molecule must be either linear or bent AB3 molecule must be either trigonal planar pr trigonal pyramidal
9.2- The VSEPR Model • A bonding pair of electrons thus defines a region in which the electrons will more likely be found. (The region is referred to as electron domain) • Nonbonding pair (lone pair) of electrons defines an electron domain that is located principally on one atom. • THE VSEPR model is based on the idea that electron domains are negatively charged & therefore, repel each other. -The VSEPR predicts that the best arrangement of electron domains is the one that minimizes the repulsions among them.
Electron domain geometry- The arrangement Of electron domains about the central atom of a Molecule or ion. *Molecular geometry is the arrangement of only the atoms in a molecule or ion. • By looking at the VSEPR model, we can predict the electron-domain geometry. -From knowing how many domains are due to Nonbonding pairs, we can then predict the Molecular geometry of a molecule or ion from Its electron-domain geometry.
Electron domain geometries • There are five….
Molecular Geometry CO2 Linear 2 electron domains
Molecular Geometry Bent Trigonal Planar Trigonal Planar NO3 BF3 3 electron domains
Molecular Geometry Trigonal Pyramidal Tetrahedral NH3 CH4 Bent Tetrahedral 4 electron domains H2O
Molecular Geometry Seesaw Trigonal Bipyramidal SF4 PCl5 Trigonal Bipyramidal T-shaped 5 electron domains Linear ClF3 XeF2
Molecular Geometry Square Pyramidal Octahedral SF6 Octahedral 6 electron domains BrF5 Square Planar XeF4
9.3 Molecular Shape & Molecular Polarity • For a molecule that consists of more than two atoms, the dipole moment depends on both the polarities of the individual bonds and the geometry of the molecule. O C O H Cl Polar Non-Polar
9.5 Hybrid Orbitals • Atomic orbitals on an atom mix to form new orbitals called hybrid orbitals. • The process of mixing atomic orbitals is called hybridization. • Provide a convenient model for using valence-bond theory to describe the covalent bonds in molecules with geometries that conform to the electron domain geometries predicted by the VSEPR model. • Steps that allow us to predict the hybrid orbitals used by an atom in the bonding: • Draw the lewis structure for the molecule or ion. • Determine the electron-domain geometry using the VSEPR model. • Specify the hybrid orbitals needed to accommodate the electron pairs based on their geometric arrangement. Example: NH3
Find: molecular formula, electron domain geometry, molecular geometry, number of electron domains(bonding/nonbonding), polarity, bond angles, hybridization Phosporushexaflouride (negative one ion) PF6
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